W. F. Cooper and H. E. Laws 
191 
We may fairly claim to have had a greater experience of the scientific 
aspect of the problem than many, who have had neither time nor 
facilities to devote to the matter. Our views on the subject have been 
confirmed both by experimental investigations and a large experience 
of practical results. 
If this paper does nothing more than to invoke discussion, or to 
lead others to put our deductions to the test by further investigation, 
we shall consider that its purpose has been achieved. 
In 1908, we were engaged by a commercial firm to make a study 
of the dipping problem at Gonubie Park, East London, S. Africa. 
A farm of 3000 acres, with 300 head of cattle, a swim bath and sufficient 
funds were placed at our disposal. A large amount of work was done, 
but the results obtained, being the property of the firm, were not 
immediately available for publication. Since then, further work has 
been carried out, detailed experiments have been continued, and, as 
permission has now been obtained to make use of such results as may 
be deemed to be of scientific interest, it is our intention to publish an 
account in the near future. 
The theoretical considerations which led up to the experiments 
carried out at Elliotdale, British East Africa, and also our dipping 
experiments in connection with the Tsetse Fly and Trypanosomiasis, 
referred to later, were based on this investigation. 
A large amount of analytical work was carried out by us at 
Gonubie Park, but unfortunately, the very limited quarters at our 
disposal soon became so thoroughly contaminated with the arsenic used 
in the preparation of large quantities of dipping materials that, though 
sufficiently good for our purpose at the time, our analytical results 
are not sufficiently reliable for the purpose of publication. Since then, 
Lieut.-Col. Watkins-Pitchford (1909, 1910 and 1911), who was working 
concurrently, though quite independently, on the same subject, has 
published results of his analyses, and as these results are readily 
available to the reader in reprint form (1911a), we have not thought 
it necessary to repeat this portion of the work, but shall make frequent 
references to this reprint. 
The Process of Dipping. 
For the benefit of English readers, to many of whom the method of 
dipping of large numbers of cattle is unfamiliar, we give the following 
brief account, omitting certain practical details which are, for the 
present purpose, unimportant • 
